Rap superstar Eminem has a prestigious new plaque to add to his collection of awards after picking up his honour as America's best-selling artist of the decade.The Without Me hitmaker, real name Marshall Mathers, was crowned the king of the charts by officials at Nielsen SoundScan, the company which compiles the Billboard countdowns, in December (09) after selling more than 32 million albums in his career to date. Eminem was presented with a special plaque commemorating his achievements this week (begs03May10) when he was joined by mentor Dr. Dre, Interscope Records boss Jimmy Iovine, manager Paul Rosenberg and Nielsen SoundScan executives Eric Weinberg and Chris Muratore for the U.S. ceremony. The hip-hop star will add to his popular back catalogue this June (10) when he releases his seventh studio album, titled Recovery.